Uncoordinated Water Research Articles

Characterization and crystal structure study of a new Cu(II) complex of pyridine-2,6-dicarboxylic acid and aniline containing a water cluster

A new monoclinic Cu(II) salt complex (C6H6N2) 2 + [Cu(2,6-dipico)2]2−·6H2O, (2,6-dipico=pyridine-2,6-dicarboxylic acid) is synthesized and characterised by CHN analyses, IR, UV-Vis, magnetic susceptibility measurements, and single crystal X-ray crystallography. The structure contains two pyridine-2,6-dicarboxylate species as tridentate ligands with protonated aniline acting as a counter cation and six uncoordinated water molecules. The complex crystallizes in the monoclinic space group C2/c with unit cell parameters a = 20.9393(4) A, b = 7.94330(10) A, c = 19.9093(4) A, V(A3) = 2932.32(9), Z = 4. Crystal packing is stabilized by N-H…O, O-H…O intermolecular hydrogen bonds and weak π…π interactions. The water molecules are trapped by a cooperative association of coordination interactions forming water clusters as well as by a hydrogen bond to the Cu (II) complex.

Structure and magnetism of a Mn(iii)–Mn(ii)–Mn(ii)–Mn(iii) chain complex

A novel tetranuclear manganese(II/III) complex with anions of pyridine-2,6-dicarboxylic acid (dipicolinic acid) has been synthesised and magneto-structurally characterised. The crystal structure of [Mn(II)2Mn(III)2(dipic)6(H2O)4]·2CH3OH·4H2O has been determined by single-crystal X-ray diffraction. The tetranuclear complex molecule [Mn(II)2Mn(III)2(dipic)6(H2O)4] is centrosymmetric and two manganese(II) and two manganese(III) atoms are bridged by four dipicolinate ligands. The complex molecules and uncoordinated water and methanol molecules are connected through hydrogen bonds and they form a 3D supramolecular hydrogen-bonding network.

Host–guest key–lock hydrogen-bonding interactions: a rare case in the design of a V-shaped polycarboxylate Ni(ii)-based chiral coordination polymer

A rare case in the design of a V-shaped polycarboxylate Ni(II)-based chiral coordination polymer from achiral ligands is described. Four metal–organic coordination networks, namely [Ni2(hfdpa)(bpypip)2(H2O)2](bpypip)·2.5H2O (1), [Ni3(Hodpa)2(bpypip)3(H2O)9] (2), [Ni2(odpa)(bpypip)2(H2O)2] (3), and [Cd2(bptc)(bpypip)2(H2O)2]·H2O (4), where H4hfdpa = 4,4′-(hexafluoroisopropylidene)diphthalic acid, H4odpa = 4,4′-oxydiphthalic acid, H4bptc = benzophenone-3,3′,4,4′-tetracarboxylic acid, and bpypip = N,N′-bis(pyrid-4-yl)piperazine, were prepared via a hydrothermal process. The structure of 1 exhibits a chiral three-dimensional porous framework, featuring left-handed Ni–O2C 21-screw helical chains along the crystallographic b axis and rectangular-shaped tubular open channels occupied by the uncoordinated bpypip and water molecules. Compound 2 possesses a 2-fold 2D + 2D → 2D interwoven sheet structure that is arranged interdigitally along the crystallographic a axis, forming an extensive three-dimensional supramolecular network through hydrogen-bonding. The structure of 3 shows a complicated 1D + 1D → 3D polyrotaxane coordination polymer entanglement, which suits a four-connected {6482}-net resembling the topology of a cds-net. Compound 4 has a complicated 2D + 2D → 3D coordination framework, which is simplified into a six-connected {496482}-net. In comparison with the crystal structures of the products, the uncoordinated bpypip ligands in 1, along with the guest water molecules, acts as a key for interacting with the coordinated V-shaped polycarboxylate hfdpa and coordinated bpypip ligands through simultaneous C–H⋯F, C–H⋯O, and C–H⋯N hydrogen-bonding, thereby assisting the generation of the chiral NiII coordination polymer. This type of host–guest key–lock interaction is unique and is observed for the first time by controlling the formation of a chiral coordination polymer.

Magnetic properties of two 2D complexes based on 1D chain containing [Fe(bpy)(CN)4]−unit

Two heterobimetallic 2-dimensional layer complexes, {[Fe(bpy)(CN)(4)](2)M(4,4'-bipyridine)}·4H(2)O [bpy = 2,2'-bipyridine, M = Mn (1), Cu (2)] have been prepared by diffusion and their structures determined by single crystal X-ray diffraction. 1 and 2 are isomorphous, made of neutral bimetallic [Fe(bpy)(CN)(4)](2)M(4,4'-bipyridine)] layers and uncoordinated water molecules located between the layers. Interestingly, complex 2 shows the compression of the Jahn-Teller distortion around the copper(II) ion. Magnetic investigation shows antiferromagnetic coupling between the manganese(II) and iron(III) ions mediated by bridging CN(-) in 1, while ferromagnetic coupling between the copper(II) and iron(III) ions is seen in 2. Both complexes 1 and 2 reveal a metamagnetic-like behaviour with different critical fields (H(c), at 1.8 K): 2.0 kOe (1) and 3.2 kOe (2). The weak interchain antiferromagnetic interaction can be illustrated by the spin-polarization mechanism.

Synthesis, characterization, and antimicrobial activity of a novel proton salt and its Cu(II) complex

A novel proton transfer compound (H2Ppz)(HDipic)2 (I) obtained from 2-(piperazin-1-yl)ethanol (Ppz) and pyridine-2,6-dicarboxylic acid (H2Dipic) and its Cu(II) complex (H2Ppz)[Cu(Dipic)2] · 6H2O (II) have been prepared and characterized by elemental, spectral (1H and 13C NMR, IR and Uv-Vis) and thermal analyses. Magnetic measurement and single crystal X-ray diffraction methods have also been applied for compound II. The molecular structure of II consists of one 1-(2-hydroxyethyl)piperazine-1,4-diium cation, one bis(pyridinium-2,6-dicarboxylate)Cu(II) anion and six uncoordinated water molecules. In complex II, the copper ion coordinates to two oxygen and one nitrogen atoms of two pyridine-2,6-dicarboxylate molecules forming an octahedral conformation. Furthermore, the synthesised compounds (I and II) were screened for their antimicrobial activities against Gram (−) (Escherichia coli and Pseudomonas aeruginosa) and Gram (+) (Staphylococcusaureus and Bacillus cereus). The results were reported, discussed and compared with the corresponding starting materials (H2Dipic and Ppz).

Catena-Poly[[[aqua(2,2′-bipyridine-κ2N,N′)zinc]-μ-furan-2,5-dicarboxylato-κ2O2:O5] dihydrate

In the title hydrated coordination polymer, {[Zn(C6H2O5)(C10H8N2)(H2O)]·2H2O}n, an infinite [1-10] chain is formed by the linking of [Zn(C10H8N2)(H2O)]2+ entities by bridging, monodentate furan-2,5-dicarboxyl­ate dianionic linkers. The Zn2+ coordination geometry is a trigonal bipyramid, with one N atom (from 2,2′-bipyridine) and one O atom (from the bridging dianion) in the axial positions. For each ZnII atom, the dihedral angle between the furan ring of its coordinated bridging ligand and its coordinated bipyridine ring system is 87.19 (8)°. O—H⋯O hydrogen bonds involving both the coordinated and uncoordinated water mol­ecules generate a layer motif parallel to (001).

A Novel Metal Organic Compound of Al(III): Synthesis, Crystal Structure, Spectroscopic and Theoretical Study

A new mononuclear compound (dmpH)[Al(pydc)2]·3H2O 1, where pydcH2 = pyridine-2,6-dicarboxylic acid and dmp = 2,9-dimethyl-1,10-phenanthroline (as known neocuproine), has been synthesized and fully characterized. The crystallographic analysis revealed that the compound 1 crystallized in Monoclinic, P21/n space group with a = 9.2625(4) A, b = 18.2798(7) A, c = 15.6002(6) A, β = 94.233(2), Z = 4, V = 2634.17(18) A3. The asymmetric unit consists of [Al(pydc)2]– anion, one dmpH+ cation and three uncoordinated water molecules. Al(III) atom is coordinated in a distorted octahedral manner by two nitrogen and four oxygen atoms of pyridine-2,6-dicarboxylate ligand. Neocuproine is known as proton acceptor ligand. In the crystal structures of the complex extensive O–H···O, N–H···O and C–H···O hydrogen bonds as well as noncovalent interactions such as π–π and C–O···π stacking play important roles in stabilizing structures. Density functional theory calculations at B3LYP/6-311++G(d,p) level was carried out to calculate geometrical parameters of studied complexes. The electronic properties of the Al(III) complex and free (pydc)2− ligand have been investigated based on the natural bond orbital analysis. AIM methodology to verify interactions between counter ion and uncoordinated water molecules with Al complex is carried out as well. Novel synthesized Al(III) compound has supramolecular structure and its calculated geometrical parameters at B3LYP/6-311++G(d,p) level are in agreement with the experimental results.

Pr2(pdc)3(Hpdc)(H2O)4]n·n(H3hp)·8n(H2O), a One-Dimensional Coordination Polymer Containing PrO6N3 Tri-Capped Trigonal Prisms and PrO8N Mono-Capped Square Anti-Prisms (H2pdc = Pyridine 2,6-Dicarboxylic Acid, C7H5NO4; 3hp = 3-Hydroxy Pyridine, C5H5NO)

The synthesis, structure and some properties of the one-dimensional coordination polymer, [Pr2(pdc)3(Hpdc)]n·n(H3hp)·8n(H2O), (H2pdc = pyridine 2,6-dicarboxylic acid, C7H5NO4; 3hp = 3-hydroxypyridine, C5H5NO) are described. One of the Pr3+ ions is coordinated by two O,N,O-tridentate pdc2− ligands and one tridentate Hpdc− anion to generate a fairly regular PrO6N3 tri-capped trigonal prism, with the N atoms acting as the caps. The second Pr3+ ion is coordinated by one tridentate pdc2− dianion, four water molecules and two monodentate bridging pdc2− ligands to result in a PrO8N coordination polyhedron that approximates to a mono-capped square-anti-prism. The ligands bridge the metal-atom nodes into a chain, which extends in the [100] direction. The H3hp+ cation and uncoordinated water molecules occupy the inter-chain regions and an N–HLO and numerous O–HLO hydrogen bonds consolidate the structure. The H3hp+ species appears to intercalate between pendant pdc rings to consolidate the polymeric structure. Crystal data: 1 (C33H43N5O29Pr2), Mr = 1255.54, triclinic, (No. 2), Z = 2, a = 13.2567(1) Å, b = 13.6304(2) Å, c = 13.6409(2) Å, α = 89.695(1)°, β = 63.049(1)°, γ = 86.105(1)°, V = 2191.16(5) Å3, R(F) = 0.033, wR(F2) = 0.084.

Tris(1,10-phenanthroline-κ2N,N′)iron(II) bis(2,4,5-tricarboxybenzoate) monohydrate and tris(2,2′-bipyridine-κ2N,N′)iron(II) 2,5-dicarboxybenzene-1,4-dicarboxylate–benzene-1,2,4,5-tetracarboxylic acid–water (1/1/2)

The title compounds, tris(1,10-phenanthroline-κ(2)N,N')iron(II) bis(2,4,5-tricarboxybenzoate) monohydrate, [Fe(C(12)H(8)N(2))(3)](C(10)H(5)O(8))(2)·H(2)O, (I), and tris(2,2'-bipyridine-κ(2)N,N')iron(II) 2,5-dicarboxybenzene-1,4-dicarboxylate-benzene-1,2,4,5-tetracarboxylic acid-water (1/1/2), [Fe(C(10)H(8)N(2))(3)](C(10)H(4)O(8))·C(10)H(6)O(8)·2H(2)O, (II), were obtained during an attempt to synthesize a mixed-ligand complex of Fe(II) with an N-containing ligand and benzene-1,2,4,5-tetracarboxylic acid via a solvothermal reaction. In both mononuclear complexes, each Fe(II) metal ion is six-coordinated in a distorted octahedral manner by six N atoms from three chelating 1,10-phenanthroline or 2,2'-bipyridine ligands. In compound (I), the Fe(II) atom lies on a twofold axis in the space group C2/c, whereas (II) crystallizes in the space group P2(1)/n. In both compounds, the uncoordinated carboxylate anions and water molecules are linked by typical O-H···O hydrogen bonds, generating extensive three-dimensional hydrogen-bond networks which surround the cations.

μ-4,4′-Bipyridine-κ2N:N′-bis[tetraaqua(4,4′-bipyridine-κN)dimanganese(II)] bis(4-aminobenzoate) bis(perchlorate)–4,4′-bipyridine–water (1/2/4): a supramolecular system constructed by π–π and hydrogen-bond interactions

The title dinuclear manganese compound, [Mn(2)(C(10)H(8)N(2))(3)(H(2)O)(8)](C(7)H(6)NO(2))(2)(ClO(4))(2)·2C(10)H(8)N(2)·4H(2)O, (I), has an inversion center located midway between the Mn(II) ions. Each Mn(II) ion has a distorted octahedral coordination environment, defined by two mutually cis N atoms from two different 4,4'-bipyridine (4,4'-bipy) ligands and four O atoms from four water molecules. The asymmetric unit contains cationic [Mn(4,4'-bipy)(1.5)(H(2)O)(4)](2+), one isolated 4,4'-bipy molecule, one 4-aminobenzoate ion, one disordered perchlorate ion and two uncoordinated water molecules. In the dinuclear manganese cationic unit, one 4,4'-bipy acts as a bidentate bridging ligand between two Mn(II) ions, while the other two act only as monodentate terminal ligands, giving rise to a 'Z-type' [Mn(2)(4,4'-bipy)(3)(H(2)O)(8)] host unit. These host units are linked to each other via face-to-face π-π stacking interactions between monodentate terminal 4,4'-bipy ligands, generating a zigzag chain. The corners of these chains, defined by Mn(OH)(4) units, are surrounded by the solvent water molecules and the carboxylate O atoms of the 4-aminobenzoate ions, and all of these are connected to each other via strong O-H···O hydrogen-bond interactions, leading to a three-dimensional grid network with a large cavity running along the b axis of the unit cell. The isolated 4,4'-bipy molecules, the 4-aminobenzoate and perchlorate anions and the water molecules are encapsulated in the cavities by numerous hydrogen-bond interactions.

μ-2,2′-(1,4-Phenylene)diacetato-κ2O1:O4]bis[aqua(2,2′-bipyridine-κ2N,N′)chloridocopper(II)] dihydrate

In the centrosymmetric title compound, [Cu2(C10H8O4)Cl2(C10H8N2)2(H2O)2]·2H2O, the CuII atom is five-coordinated in a distorted square-pyramidal geometry by two N atoms from a chelating 2,2′-bipyridine ligand, one O atom from a 1,4-phenyl­enediacetate ligand, one Cl atom and one water mol­ecule. The 1,4-phenyl­enediacetate ligand, lying on an inversion center, bridges two CuII atoms. In the crystal, O—H⋯O and O—H⋯Cl hydrogen bonds and π–π inter­actions between the pyridine rings [centroid–centroid distance = 3.740 (5) Å] link the complex mol­ecules and uncoordinated water mol­ecules into a three-dimensional network.

Chloridobis[2-(1,3-thiazol-4-yl-κN)-1H-benzimidazole-κN3]cobalt(II) chloride dihydrate

In the title compound, [CoCl(C10H7N3S)2]Cl·2H2O, the CoII atom is five-coordinated by four N atoms from two chelating 2-(1,3-thia­zol-4-yl)-1H-benzimidazole ligands and one Cl atom in a distorted trigonal–bipyramidal geometry. In the crystal, N—H⋯O and O—H⋯Cl hydrogen bonds and π–π inter­actions between the thia­zole, imidazole and benzene rings [centroid-to-centroid distances 3.546 (2), 3.683 (2) and 3.714 (2) Å] link the complex cations, chloride anions and uncoordinating water mol­ecules into a three-dimensional network.

3-(Aminocarbonyl)pyridinium diaqua-bis(pyridine-2,6-dicarboxylato)bismuthate(III) monohydrate

The asymmetric unit of the ionic title compound, (C6H7N2O)[Bi(C7H3NO4)2(H2O)2]·H2O or (acpyH)[Bi(pydc)2(H2O)2]·H2O, contains an [Bi(pydc)2(H2O)2]− anion (where pydcH2 is pyridine-2,6-dicarb­oxy­lic acid), a protonated 3-(amino­carbon­yl)pyridine as counter-ion, (acpyH)+, and one uncoordinated water mol­ecule. The anion is an eight-coordinate complex with a square-anti­prismatic geometry around the BiIII atom. In the crystal, extensive O—H⋯O and N—H⋯O hydrogen bonds, as well as ion pairing, C=O⋯π inter­actions [O⋯centroid distance = 3.583 (5) Å], π–π stacking [centroid–centroid distance = 3.864 (3) Å], and C—H⋯π and C—H⋯O inter­actions, play an important role in the formation and stabilization of the three-dimensional supra­molecular structure.

Poly[[hexa-μ-aqua-diaquabis(μ4-dihydrogen benzene-1,2,4,5-tetracarboxylato)magnesiumdisodium] dihydrate

The asymmetric unit of the title compound, {[MgNa2(C10H4O8)2(H2O)8]·2H2O}n, contains one octa­hedrally coordin­ated MgII atom (site symmetry 2/m), one octahedrally coordinated NaI atom (site symmetry 2) and one half of the dihydrogen benzene-1,2,4,5-tetra­carboxyl­ate (btec) ligand, the second half of the ligand being generated by a twofold rotation axis. The basic framework of the title compound features infinite (–Na–Na–Mg–)n chains along [10-1] with the metal cations bridged by the coordinating water molecules. The chains are isolated from each other by μ4-bridging btec ligands, which form inter­molecular O—H⋯O hydrogen bonds to uncoordinated water mol­ecules and the coordinated water mol­ecules of a neighbouring chain. In each btec ligand, there are also intramolecular O—H⋯O hydrogen bonds.

Aquasoluble iron(III)-arylhydrazone-β-diketone complexes: Structure and catalytic activity for the peroxidative oxidation of C5–C8 cycloalkanes

The aquasoluble FeIII complexes [Fe(H2O)3(L1)]∙4H2O (3) and [Fe(H2O)3(L2)]∙3H2O (4), bearing the basic forms of 5-chloro-3-(2-(4,4-dimethyl-2,6-dioxocyclohexylidene)hydrazinyl)-2-hydroxy-benzenesulfonic acid (H3L1, 1) and 3-(2-(2,4-dioxopentan-3-ylidene)hydrazinyl)-2-hydroxy-5-nitrobenzenesulfonic acid (H3L2, 2), were synthesized and fully characterized including by X-ray crystal structural analysis. In the channels of the water-soluble 3D networks of 3 and 4, the uncoordinated water molecules are held by oxygen atoms of the carbonyl and sulfonyl groups, and by the water ligands. The FeIII coordination environment resembles that in the active sites of some mononuclear non-heme iron-containing enzymes. The complexes show a high catalytic activity for the peroxidative oxidation (with aqueous H2O2) of C5–C8 cycloalkanes to the corresponding alcohols and ketones under mild conditions. The effects of various factors, such as amounts of oxidant, catalyst and HNO3 additive, were investigated allowing to reach overall yields of ca. 25% and turnover numbers (TONs) up to 290. The catalytic reactions proceed via both oxygen- and carbon-radicals as shown by radical trap experiments.

2-Amino-5-chloropyridinium cis-diaquadioxalatochromate(III) sesquihydrate

In the crystal structure of the title compound, (C5H6ClN2)[Cr(C2O4)2(H2O)2]·1.5H2O, the CrIII atom adopts a distorted octa­hedral geometry being coordinated by two O atoms of two cis water mol­ecules and four O atoms from two chelating oxalate dianions. The cis-diaqua­dioxalatochromate(III) anions, 2-amino-5-chloro­pyridinium cations and uncoordinated water mol­ecules are linked into a three-dimensional supra­molecular array by O—H⋯O and N—H⋯O hydrogen-bonding inter­actions. One of the two independent lattice water molecules is situated on a twofold rotation axis.

Evaluation of the Impact of H2O, O2, and SO2 on Postcombustion CO2 Capture in Metal–Organic Frameworks

Molecular modeling methods are used to estimate the influence of impurity species: water, O(2), and SO(2) in flue gas mixtures present in postcombustion CO(2) capture using a metal organic framework, HKUST-1, as a model sorbent material. Coordinated and uncoordinated water effects on CO(2) capture are analyzed. Increase of CO(2) adsorption is observed for both cases, which can be attributed to the enhanced binding energy between CO(2) and HKUST-1 due to the introduction of a small amount of water. Density functional theory calculations indicate that the binding energy between CO(2) and HKUST-1 with coordinated water is ~1 kcal/mol higher than that without coordinated water. It is found that the improvement of CO(2)/N(2) selectivity induced by coordinated water may mainly be attributed to the increased CO(2) adsorption on the hydrated HKUST-1. On the other hand, the enhanced selectivity induced by uncoordinated water in the flue gas mixture can be explained on the basis of the competition of adsorption sites between water and CO(2) (N(2)). At low pressures, a significant CO(2)/N(2) selectivity increase is due to the increase of CO(2) adsorption and decrease of N(2) adsorption as a consequence of competition of adsorption sites between water and N(2). However, with more water molecules adsorbed at higher pressures, the competition between water and CO(2) leads to the decrease of CO(2) adsorption capacity. Therefore, high pressure operation should be avoided in HKUST-1 sorbents for CO(2) capture. In addition, the effects of O(2) and SO(2) on CO(2) capture in HKUST-1 are investigated: The CO(2)/N(2) selectivity does not change much even with relatively high concentrations of O(2) in the flue gas (up to 8%). A slightly lower CO(2)/N(2) selectivity of a CO(2)/N(2)/H(2)O/SO(2) mixture is observed compared with that in a CO(2)/N(2)/H(2)O mixture, especially at high pressures, due to the strong SO(2) binding with HKUST-1.

9-Aminoacridinium bis(pyridine-2,6-dicarboxylato-κ3 O 2,N,O 6)ferrate(III) tetrahydrate

The asymmetric unit of the title compound, (C13H11N2)[Fe(C7H3NO4)2]·4H2O, contains a 9-amino­acridinium cation, one anionic complex and four uncoordinated water mol­ecules. In the anionic complex, the FeIII ion is six-coordinated by two almost perpendicular [dihedral angle = 88.78 (7)°] pyridine-2,6-dicarboxyl­ate ligands in a distorted octa­hedral geometry. In the crystal, anions are connected into chains along [10-1] by weak C—H⋯O inter­actions, which create ten-membered hydrogen-bonded R 2 2(10) rings. These chains are linked by three-membered water clusters. The final three-dimensional network is constructed by numerous inter­molecular O—H⋯O and N—H⋯O inter­actions.

Supramolecularly assembled tetrameric water cluster stabilized by a mixed complex of Ni(II) and 5-aminoisophthalate

In this study, a novel Ni(II)-5-aminoisophthalate (aip) complex with 5-methylimidazole (5-meim), [Ni(5-meim)6]2(aip)2⋅8H2O (1) has been synthesized. Elemental analysis, magnetic susceptibility, IR and UV–Vis. spectroscopic studies have been performed to characterize the compound. The molecular structure of 1 has been determined by the single crystal X-ray diffraction technique. The complex consists of two hexa(5-methylimidazole)nickel(II) cations, two uncoordinated 5-aminoisophthalate anions and eight uncoordinated water molecules. The molecular structure of (1) has been determined by the single crystal X-ray diffraction technique. In (1) Ni(II) ion has distorted octahedral geometry. The complex (1) is further constructed to form three-dimensional framework by hydrogen bonding, CH⋯π and π⋯π stacking interactions.

Catena-Poly[[[diaquanickel(II)]-μ-pyrazine-2-carboxylato-silver(I)-μ-pyrazine-2-carboxylato] nitrate dihydrate

In the polymeric complex of the title compound, {[AgNi(C5H3N2O2)2(H2O)2]NO3·2H2O}n, the AgI ion displays an angular coordination geometry with two N atoms from pyrazine-2-carboxyl­ate ligands, and the NiII ion is hexa­coordinated by two O atoms from two water mol­ecules, two O and two N atoms from pyrazine-2-carboxyl­ate ligands in a distorted octa­hedral geometry. In the crystal, the AgI and NiII ions lie on a mirror plane and an inversion centre, respectively. The complex chains, the nitrate ions and the uncoordinated water mol­ecules are linked together through O—H⋯O hydrogen bonds and weak Ag⋯O inter­actions [2.619 (17)–2.749 (17) Å] into a three-dimensional network.